Therapeutic vascular occlusion (i.e., embolization) is used to prevent or treat certain pathological conditions in situ. It can be administered by means of catheters making it possible, under imagery control, to position particulate occlusion agents (i.e., emboli) in the circulatory system. It has a variety of medical applications such as in the treatment of tumors, including, e.g., uterine fibroids, vascular malformations and hemorrhagic processes. For example, vascular occlusion can suppress pain, limit blood loss on the surgical intervention to follow embolization or even bring on a tumoral necrosis and avoid the operation. In the case of vascular malformations, vascular occlusion enables the blood flow to the normal tissues to be normalized, aids in surgery and limits the risk of hemorrhage. In the hemorrhagic processes, vascular occlusion can produce a reduction of flow, which promotes cicatrisation of the arterial opening(s). Moreover, depending on the pathological conditions treated, embolization can be used for temporary as well as permanent purposes.
Different types of emboli have been used for embolization, for example, liquid agents (e.g., acrylic glues, gels or viscous suspensions) as well as particulate agents (e.g., miscellaneous polymers, dura mater, gelatin sponges, spheres, balloons or spirals), including EmboSphere® trisacryl gelatin microspheres (BioSphere Medical, Rockland, Mass.) (see also, e.g., U.S. Pat. Nos. 5,635,215 and 5,648,100).
Among the various occlusion agents, microspheres have demonstrated better embolic properties over other solid emboli. However, the quality and yield of the microspheres often varies due to materials used in the production process and methods of making them.
Accordingly, there remains a need for methods of producing microspheres with, e.g., a better yield productivity and possibly better uniformity or purity. In addition, there also remains a need for microspheres with, for example, a better or more consistent quality from production batch to production batch that are capable of providing optimized embolic effects.